INTRODUCTION:There is a lack of consistent study findings on associations between workplace exposures and the risk of Parkinson disease (PD) and a paucity of such data on women. We assessed PD risk among occupational groups to derive insights about potential occupation-specific exposures in a large cohort of women. METHODS:The Women's Health Initiative Observational Study (WHI-OS) is a prospective cohort that enrolled 91 627 postmenopausal women, 50 to 79 years of age, from 01 October 1993 through 31 December 1998, at 40 clinical centers across the United States, with average follow-up interval of 11 years. These women reported up to three paid jobs, held the longest since age 18; these jobs were coded and duration of employment calculated. We defined a case by self-report of doctor-diagnosed PD (at baseline or follow-up), death attributed to PD, or taking medication consistent with PD. RESULTS:Among 2590 PD cases, we found evidence of excess risk among "counselors, social workers, and other community and social service specialists," and there was a suggestion of increased in risk among postsecondary teachers, and "building and grounds cleaning and maintenance" workers. There was also evidence of a deficit in risk among women who worked in sales. Results according to ever-employed and job duration were similar, except for evidence of excess risk among "health technologists and technicians" with more than 20 years of employment. Longer duration of life on a farm was associated with higher risk. CONCLUSION:Our findings paint a largely reassuring picture of occupational risks for PD among US women.